Water skiing involves many different components of physics. The fundamentals of it are based mainly on angles and gravity. When you are trying to get up, you have to make sure you keep your ski at a certain angle so that the water pushes down on the ski, creating a downward force that enables you to stand up. Once the force of the water pushing up on the ski is equal to the force of gravity pulling down on the ski, you are able to stay on top of the water.
Tension is also involved in water skiing because the rope from the boat to your hand pulls tightly, creating tension. When the tension in the rope is constant, you will be traveling at the same speed as the boat pulling you. However, since the rope from the boat to the water skier keeps you moving in a circular path. Since you are moving in a circular path, there is also centripetal force. When the centripetal force is high, the water skier may be moving faster than the boat itself.